The simplified mass relations [1]} for light active neutrinos and sterile neutrinos
is given by
\(&& m_\nu = - M_DM_R^{-1}M_D^T , \nonumber \\[1mm]&& M_{D}=-\iota UD_{\sqrt{m_\nu }}R^TD_{\sqrt{M_R}}= y_{\nu }v/\sqrt{2}.\) 
